Boeing 707
The Boeing 707 is a mid-sized, long-range, , built by from 1958 to 1979. Its name is commonly pronounced as "seven oh seven". Versions of the aircraft have a capacity from 140 to 219 passengers and a range of 2,500 to 5,750 (2,880 to 6,620 mi; 4,630 to 10,650 km). Developed as Boeing's first jet airliner, the 707 is a swept-wing design with . Although it was not the first jetliner in service, the 707 was the first to be commercially successful. Dominating passenger in the 1960s and remaining common through the 1970s, the 707 is generally credited with ushering in the . It established Boeing as one of the largest manufacturers of passenger aircraft, and led to the later series of airliners with "" designations. The later , , , and share elements of the 707's fuselage design. The 707 was developed from the , a jet first flown in 1954. A larger fuselage cross-section and other modifications resulted in the initial-production 707-120, powered by engines, which first flew on December 20, 1957. began regular 707 service on October 26, 1958. Later derivatives included the shortened long-range 707-138 and the stretched 707-320, both of which entered service in 1959. A smaller short-range variant, the , was introduced in 1960. The 707-420, a version of the stretched 707 with , debuted in 1960, while turbofans debuted on the 707-120B and 707-320B models in 1961 and 1962, respectively. The 707 has been used on , , and flights, and for cargo and military applications. A convertible passenger-freighter model, the 707-320C, entered service in 1963, and passenger 707s have been modified to freighter configurations. Military derivatives include the airborne reconnaissance aircraft and the VIP transports. Boeing produced and delivered 1,011 airliners including the smaller 720 series; over 800 military versions were also produced. Contents ** ** ** ** *** * ** ** ** ** ** ** ** ** ** *** * ** ** * * * * ** ** ** * Development[] Model 367-80 origins[] Main article: The 707 was based on the Dash 80 During and after World War II, Boeing was known for its military aircraft. The company had produced innovative and important bombers, from the and , to the jet-powered and . The company's civil aviation department lagged far behind and other competitors, the only noteworthy airliners being the and . During 1949–1950, Boeing embarked on studies for a new jet transport, realizing that any design must be aimed at both the military and civilian markets. At the time, was becoming a standard technique for military aircraft, with over 800 on order. With the advent of the , a new tanker was required to meet the USAF's fleet of jet-powered bombers; this was where Boeing's new design would potentially win military orders. Boeing studied numerous wing and engine layouts for its new transport/tanker, some of which were based on the B-47 and C-97, before settling on . The "Dash 80" took less than two years from project launch in 1952 to rollout on May 14, 1954, then first flew on July 15, 1954. It was powered by the engine, which was the civilian version of the used on many military aircraft of the day, including the fighter and the B-52 bomber. The prototype was a proof-of-concept aircraft for both military and civilian use. The was the first customer, using it as the basis for the aerial refueling platform. Whether the passenger 707 would be profitable was far from certain. At the time, Boeing was making nearly all of its money from military contracts: Its last passenger transport, the , had netted the company a $15 million loss before it was purchased by the Air Force as the KC-97 Stratofreighter. In a demonstration flight over Lake Washington outside Seattle, on August 7, 1955, test pilot performed a in the 367-80 prototype. Boeing 707-123B cockpit The 132 in (3,352.80 mm) wide fuselage of the Dash 80 was large enough for four-abreast (two-plus-two) seating like the Stratocruiser. Answering customers' demands and under Douglas competition, Boeing soon realized this would not provide a viable payload, so it widened the fuselage to 144 in (3,660 mm) to allow five-abreast seating and use of the KC-135's tooling. Douglas Aircraft had launched its with a fuselage width of 147 in (3,730 mm). The airlines liked the extra space and six-abreast seating, so Boeing increased the 707's width again to compete, this time to 148 in (3,760 mm). Production and testing[] Members of the joint FAA and Boeing team performing test flight on the Boeing 707 during certification process in April 15, 1958: From left to right: (FAA), Lew Wallich (Boeing), unknown, unknown The first flight of the first-production 707-120 took place on December 20, 1957, and FAA certification followed on September 18, 1958. Both test pilots and James R. Gannett were awarded the first for the test flights that led to certification. A number of changes were incorporated into the production models from the prototype. A was installed along the leading edge between the inner and outer engines on early 707-120 and −320 models. Further developments[] Early production Boeing 707–329 of in April 1960 with the original short tail-fin and no ventral fin The initial standard model was the 707-120 with JT3C turbojet engines. ordered a shorter-bodied version called the 707-138, which was a −120 with six fuselage frames removed, three in front of the wings, and three aft. The frames in the 707 were each 20 in (510 mm) apart, so this resulted in a net shortening of 10 ft (3.0 m) to 134 ft 6 in (41.0 m). Because the maximum takeoff weight remained the same as that of the −120 (247,000 lb (112 t)), the −138 was able to fly the longer routes that Qantas needed. ordered the higher-thrust version with A engines, the 707-220. The final major derivative was the 707-320, which featured an extended-span wing and JT4A engines, while the 707-420 was the same as the −320, but with turbofan engines. British relating to with one engine inoperative also forced Boeing to increase the height of the on all 707 variants, as well as add a , which was retrofitted on earlier −120 and −220 aircraft. These modifications also aided in the mitigation of by providing more stability in . A Boeing 707 at during the state visit of Pakistan President to Germany, January 1961 Though initially fitted with turbojet engines, the dominant engine for the Boeing 707 family was the , a variant of the JT3C with lower fuel consumption and higher thrust. JT3D-engined 707s and 720s were denoted with a "B" suffix. While many 707-120Bs and -720Bs were conversions of existing JT3C-powered machines, 707-320Bs were available only as newly built aircraft, as they had a stronger structure to support a maximum takeoff weight increased by 19,000 lb (8,600 kg), along with modifications to the wing. The 707-320B series enabled nonstop westbound flights from Europe to the US West Coast and from the US to Japan. The final 707 variant was the 707-320C, (C for "Convertible"), which had a large fuselage door for cargo. It had a revised wing with three-sectioned leading-edge flaps, improving takeoff and landing performance and allowing the ventral fin to be removed (although the taller fin was retained). The 707-320Bs built after 1963 used the same wing as the −320C and were known as 707-320B Advanced aircraft. Production of the passenger 707 ended in 1978. In total, 1,010 707s were built for civilian use, though many of these found their way to military service. The 707 production line remained open for purpose-built military variants until 1991, with the last new-build 707 airframes built as and aircraft. Traces of the 707 are still found in the , which uses a modified version of the 707's fuselage, as well as the same external nose and cockpit configurations as those of the 707. These were also used on the previous , while the also used the 707 fuselage cross-section. Design[] Wings[] Four-wheel landing-gear bogies on a 707–120 The 707's wings are swept back at 35°, and like all swept-wing aircraft, display an undesirable "" flying characteristic that manifests itself as an alternating yawing and rolling motion. Boeing already had considerable experience with this on the B-47 and B-52, and had developed the system on the B-47 that would be applied to later swept-wing configurations like the 707. However, many novice 707 pilots had no experience with this phenomenon, as they were transitioning from straight-wing propeller-driven aircraft such as the and . On one customer-acceptance flight, where the yaw damper was turned off to familiarize the new pilots with flying techniques, a trainee pilot's actions violently exacerbated the Dutch roll motion and caused three of the four engines to be torn from the wings. The plane, a brand new 707-227, N7071, destined for Braniff, crash-landed on a river bed north of Seattle at , killing four of the eight occupants. In his autobiography, Tex Johnston describes a Dutch roll incident he experienced as a passenger on an early commercial 707 flight. As the aircraft's movements did not cease and most of the passengers became ill, he suspected a misrigging of the directional autopilot (yaw damper). He went to the cockpit and found the crew unable to understand and resolve the situation. He introduced himself and relieved the ashen-faced captain who immediately left the cockpit feeling ill. Johnston disconnected the faulty autopilot and manually stabilized the plane "with two slight control movements". Engines[] View of number 1 (top left) and 2 (center) Pratt & Whitney JT3D engines on the side of a Boeing 707-320C: The number 1 engine mount does not have the "hump" for a pressurization turbocompressor. The 707 uses engine-driven to supply pressurized air for . On many commercial 707s, the outer port (number 1) engine mount is distinctly different from the other three, as this engine is not fitted with a turbocompressor. Later-model 707s typically had this configuration, although American Airlines had turbocompressors on engines 2 and 3 only. Early 707 models often had turbocompressor fairings on all four engines, but with only two or three compressors installed. The JT3D-3B engines are readily identifiable by the large gray secondary air inlet doors in the nose cowl. These doors are fully open (sucked in at the rear) during takeoff to provide additional air. When the engines are throttled back to cruise, the doors are shut. The 707 was the first commercial jet aircraft to be fitted with clamshell-type on each of the four engines. Upgraded engines[] Omega Air's 707-330C testbed for the 707RE program takes off from the Pratt & Whitney, in a joint venture with Seven Q Seven (SQS) and Omega Air, has selected the as a re-engine powerplant for Boeing 707-based aircraft, calling their modified configuration a 707RE. Northrop Grumman has selected the −219 to re-engine the United States Air Force's fleet of 19 aircraft, which will allow the J-STARS more time on station due to the engine's greater fuel efficiency. also plans to re-engine their fleet of E-3 Sentry AWACS aircraft. The −219 is publicized as being half the cost of the competing 707 re-engine powerplant, the , and is 40 dB quieter than JT3D engines that are being replaced. Operational history[] The first commercial orders for the 707 came on October 13, 1955, when committed to 20 707s and 25 Douglas DC-8s, dramatically increasing their passenger capacity (in available revenue passenger seat-miles per hour/per day) over its existing fleet of propeller aircraft. The competition between the 707 and was fierce. Pan American ordered these planes, when and as they did, so that they would be the operators of the "first-off" production line for each aircraft type. Until their initial batch of the aircraft had been delivered to them and put into operation, Pan American would have the distinction of being not only the "Launch Customer" for both transcontinental American jets, but the exclusive operator of American intercontinental jet transports for at least a year. 's Jet Clipper America, a 707-121, at after completing the first commercial flight of the 707 in October 1958. The only rival in intercontinental jet aircraft production at the time was the British . However, this was never real competition for the American market as the Comet series had been the subject of (due to design flaws) early in its introduction, withdrawn from service, virtually redesigned from scratch, and reintroduced as version -4. It was also smaller and slower than the 707. Several major airlines committed only to the (second place in the production race) Douglas DC-8. Douglas Aircraft was the more established and preferred (by airlines and their passengers) maker of passenger aircraft at the time. Douglas had correctly decided to await the validation of a larger and more fuel efficient engine ( from ) and to design a larger and longer range aircraft around this engine. To stay competitive, Boeing made a late and costly decision to redesign and enlarge the 707's wing to help increase range and payload. The new version was numbered 707-320. Pan Am was the first airline to operate the 707; the carrier inaugurated 707 service with a christening at on October 17, 1958, attended by , followed by a transatlantic flight for VIPs (personal guests of founder ) from to Paris. The aircraft's first commercial flight was from , New York, to , Paris, on October 26, 1958, with a fuel stop in . In December, operated the first U.S. domestic jet airline flights between and Miami, using 707s leased from Pan Am; was the first domestic airline to fly its own jets, on January 25, 1959. TWA started domestic 707-131 flights in March and started 707-124 flights in June; airlines that had ordered only the DC-8, such as , , and , were left without jets until September and lost market share on transcontinental flights. Qantas was the first non-US airline to use the 707s, starting in 1959. An Boeing 707–328 at , 1972 The 707 quickly became the most popular jetliner of its time. Its popularity led to rapid developments in airport terminals, runways, airline catering, baggage handling, reservations systems, and other air transport infrastructure. The advent of the 707 also led to the upgrading of systems to prevent interference with military jet operations. As the 1960s drew to a close, the exponential growth in air travel led to the 707 being a victim of its own success. The 707 was now too small to handle the increased numbers of passengers on the routes for which it was designed. Stretching the fuselage was not a viable option because the installation of larger, more powerful engines would need a larger undercarriage, which was not feasible given the design's limited ground clearance at takeoff. Boeing's answer to the problem was the first airliner—the . The 707's first-generation engine technology was also rapidly becoming obsolete in the areas of noise and fuel economy, especially after the . 707 landing at in 2011: Saha Airlines was the last commercial operator of the 707. In 1982, during the , the extensively used 707s for long-range , with some of them being intercepted and shepherded away by Royal Navy , it also led to the conversion of British to carry air-to-air missiles after a casual encounter. Operations of the 707 were threatened by the enactment of international noise regulations in 1985. Shannon Engineering of Seattle developed a with funding from , of Austin, Texas. By the late 1980s, 172 Boeing 707s had been equipped with the Quiet 707 package. Boeing acknowledged that more 707s were in service than before the hush kit was available. flew the last scheduled 707 flight for passengers by a US carrier on October 30, 1983, although 707s remained in scheduled service by airlines from other nations for much longer. of flew 707s and 720s in front-line passenger service until the end of the 1990s. Since of took its 707-320Bs from regular service in 2007, of was the last airline to keep 707s in scheduled passenger service until April 2013, though it continued to use them for charter cargo flights until 2019, when their final 707 on lease . As of 2019, only a handful of 707s remain in operation, acting as military aircraft for , transport, and missions. Variants[] Although certified as Series 100s, 200s, 300s, etc., the different 707 variants are more commonly known as Series 120s, 220s, 320s, and so on, where the "20" part of the designation is Boeing's for its development aircraft. 707-020[] Main article: The 707-020 was the original designation for what ultimately became the . Launch customer United Air Lines was a Douglas DC-8 customer and preferred not to be seen as buying the competing 707, hence the 720 designation. American Airlines always referred to its 720s as 707s. 707-120[] Turkish Airlines 707-121B in 1976 The 707-120 was the first production 707 variant, with a longer, wider fuselage, and greater wingspan than the Dash 80. The cabin had a full set of rectangular windows and could seat up to 189 passengers. It was designed for transcontinental routes, and often required a refueling stop when flying across the North Atlantic. It had four Pratt & Whitney JT3C-6 turbojets, civilian versions of the military J57, initially producing 13,000 lbf (57.8 kN) with . Maximum takeoff weight was 247,000 lb (112,000 kg) and first flight was on December 20, 1957. Major orders were the launch order for 20 707-121 aircraft by Pan Am and an American Airlines order for 30 707-123 aircraft. The first revenue flight was on October 26, 1958; 56 were built, plus seven short-bodied −138s; the last −120 was delivered to Western in May 1960. The 707-138 was a −120 with a fuselage 10 ft (3.0 m) shorter than the others, with 5 ft (1.5 m) (three frames) removed ahead and behind the wing, giving increased range. Maximum takeoff weight was the same 247,000 lb (112,000 kg) as the standard version. It was a variant for Qantas, thus had its 38. The seven −138s were delivered to Qantas June–September 1959 and first carried passengers that July. A 707-120B () wing, showing the new inboard leading edge like the 720s at , Seattle, 2009. The 707-120B had Pratt & Whitney JT3D-1 turbofan engines, which were quieter, more powerful, and more fuel-efficient, producing 17,000 lbf (75.6 kN) each, with the later JT3D-3 version giving 18,000 lbf (80 kN). (This thrust did not require water injection, eliminating both the system and 5000–6000 lb of water.) The −120B had the wing modifications introduced on the 720 and a longer tailplane; a total of 72 were built, 31 for American and 41 for TWA, plus six short-bodied −138Bs for Qantas. American had its 23 surviving −123s converted to 123Bs, but TWA did not convert its 15 -131s. The only other conversions were Pan American's five surviving −121s and one surviving −139, the three aircraft delivered to the USAF as −153s and the seven short-bodied Qantas −138s. The first flight of the −120B was on June 22, 1960, and American carried the first passengers in March 1961; the last delivery was to American in April 1969. Maximum weight was 258,000 lb (117,000 kg) for both the long- and short-bodied versions. 707-220[] The 707-220 was designed for operations with more powerful 15,800 lbf (70.3 kN) turbojets. Five of these were produced, but only four were ultimately delivered, with one being lost during a test flight. All were for Braniff International Airways and carried the model number 707-227; the first entered service in December 1959. This version was made obsolete by the arrival of the turbofan-powered 707-120B. 707-320[] The 707-320 Intercontinental is a stretched version of the turbojet-powered 707-120, initially powered by JT4A-3 or JT4A-5 turbojets producing 15,800 lbf (70.3 kN) each (most eventually got 17,500 lbf (77.8 kN) JT4A-11s). The interior allowed up to 189 passengers, the same as the -120 and -220 series, but improved two-class capacity due to an 80-in fuselage stretch ahead of the wing (from 138 ft 10 in (42.32 m) to 145 ft 6 in (44.35 m) ), with extensions to the fin and horizontal stabilizer extending the aircraft's length further. The longer wing carried more fuel, increasing range by 1,600 miles (2,600 km) and allowing the aircraft to operate as true transoceanic aircraft. The wing modifications included outboard and inboard inserts, as well as a kink in the trailing edge to add area inboard. Takeoff weight was increased to 302,000 lb (137,000 kg) initially and to 312,000 lb (142,000 kg) with the higher-rated JT4As and center section tanks. Its first flight was on January 11, 1958; 69 turbojet 707-320s were delivered through January 1963, the first passengers being carried (by Pan Am) in August 1959. 707-420[] Conway-powered 707-436 at in 1970 The 707-420 was identical to the −320, but fitted with Rolls-Royce Conway 508 (RCo.12) turbofans (or by-pass turbojets as Rolls-Royce called them) of 18,000 lbf (80 kN) thrust each. The first announced customer was . 's controversial order was announced six months later, but the British carrier got the first service-ready aircraft off the production line. The British refused to give the aircraft a certificate of airworthiness, citing insufficient lateral control, excessive rudder forces, and the ability to over-rotate on takeoff, stalling the wing on the ground (a fault of the de Havilland Comet 1). Boeing responded by adding 40 inches to the vertical stabilizer, applying full instead of partial rudder boost, and fitting an underfin to prevent over-rotation. These modifications except to the fin under the tail became standard on all 707 variants and were retrofitted to all earlier 707s. The 37 -420s were delivered to , , , , and through November 1963; Lufthansa was the first to carry passengers, in March 1960. 707-320B[] A Boeing 707-320B of Pan American World Airways in 1979 The 707-320B had the application of the JT3D turbofan to the Intercontinental, but with aerodynamic refinements. The wing was modified from the −320 by adding a second inboard kink, a dog-toothed leading edge, and curved low-drag wingtips instead of the earlier blunt ones. These wingtips increased overall wingspan by 3.0 ft. Takeoff gross weight was increased to 328,000 lb (149,000 kg). The 175 707-320B aircraft were all new-build; no original −320 models were converted to fan engines in civilian use. First service was June 1962, with Pan Am. The 707-320B Advanced is an improved version of the −320B, adding the three-section leading-edge flaps already seen on the −320C. These reduced takeoff and landing speeds and altered the lift distribution of the wing, allowing the ventral fin found on earlier 707s to be deleted. From 1965, -320Bs had the uprated −320C undercarriage allowing the same 335,000 lb (152,000 kg) MTOW. These were often identified as 707-320BA-H. 707-320C[] 707-321C in January 1987 The 707-320C has a convertible passenger–freight configuration, which became the most widely produced variant of the 707. The 707-320C added a strengthened floor and a new cargo door to the −320B model. The wing was fitted with three-section leading-edge flaps which allowed the deletion of the underfin. Three hundred and thirty-five of these variants were built, including a small number with JT3D-7 engines (19,000 lbf (85 kN) takeoff thrust) and a takeoff gross weight of 335,000 lb (152,000 kg). Ironically, most −320Cs were delivered as passenger aircraft, airlines hoping that the cargo door would increase second-hand values. The addition of two additional emergency exits, one on either side aft of the wing raised the maximum passenger capacity to a theoretical 219. Only a few aircraft were delivered as pure freighters. One of the final orders was by the Iranian Government for 14 707-3J9C aircraft capable of VIP transportation, communication, and in-flight refuelling tasks. 707-700[] The 707-700 was a test aircraft used to study the feasibility of using engines on a 707 airframe and possibly retrofitting existing aircraft with the engine. After testing in 1979, N707QT, the last commercial 707 airframe, was restored to 707-320C configuration and delivered to the Moroccan Air Force as a tanker aircraft via a "civilian" order. Boeing abandoned the retrofit program, since it felt it would be a threat to the program. The information gathered from testing led to the eventual retrofitting of CFM56 engines to the USAF C-135/KC-135R models, and some military versions of the 707 also used the CFM56. The Douglas DC-8 "Super 70" series with CFM56 engines was developed and extended the DC-8's life in a stricter noise regulatory environment. So, more DC-8s than 707s are in service now. Other variants[] The 707-620 was a proposed domestic range-stretched variant of the 707-320B. The 707-620 was to carry around 200 passengers while retaining several aspects of the 707-320B. It would have been delivered around 1968 and would have also been Boeing's answer to the stretched . Had the 707-620 been built, it would have cost around US$8,000,000. However, engineers discovered that a longer fuselage and wing meant a painstaking redesign of the wing and landing-gear structures. Rather than spend money on upgrading the 707, engineer stated the company "decided spending money on the 707 wasn't worth it". The project was cancelled in 1966 in favor of the newer . The 707-820 was a proposed intercontinental stretched variant of the 707-320B. It was to be powered by four Pratt & Whitney JT3D-15 turbofan engines and would have had a 10-foot (3.0 m) extension in wingspan. Two variations were proposed, the 707-820(505) model and the 707-820(506) model. The 505 model would have had a fuselage 45 feet (14 m) longer than the 707-320B and would have carried 209 passengers in mixed-class configuration and 260 passengers in all-economy configuration. The 506 model would have had a fuselage 55 feet (17 m) longer than the 707-320B and would have carried 225 passengers in mixed class configuration and 279 passengers in all economy configuration. Like the 707-620, the 707-820 was also set to compete with the stretched DC-8s. The design was being pitched to American, TWA, BOAC, and Pan Am at the time of its proposal in early 1965. The 707-820 would have cost US$10,000,000. Like the 707-620, the 707-820 would have required a massive structural redesign to the wing and gear structures. The 707-820 was also cancelled in 1966 in favor of the 747. Military[] USAF E-3 Sentry in flight, 2002 RAAF 707-368C at Perth International Airport, Australia, 2004 Boeing 707s at being used for salvage parts for the KC-135s, 2005 Main articles: , , , , and The militaries of the US and other countries have used the civilian 707 aircraft in a variety of roles, and under different designations. (The 707 and U.S. Air Force's KC-135 were developed in parallel from the Boeing 367–80 prototype.) The is a US military (AWACS) aircraft based on the Boeing 707 that provides all-weather surveillance, command, control, and communications. The VC-137C variant of the Stratoliner was a special-purpose design meant to serve as , the secure transport for the . These models were in operational use from 1962 to 1990. The two aircraft remain on display: is at the near and is at the in . The also operated the Boeing 707 with the designation (707-347C) from 1971 to 1997. 717[] Boeing 717 was the company designation for C-135 Stratolifter and KC-135 Stratotanker derivatives of the 367-80. The designation was later reused in renaming the McDonnell Douglas MD-95 to after the company was merged with Boeing. Operators[] See also: Boeing's customer codes used to identify specific options and livery specified by customers was started with the 707, and has been maintained through all Boeing's models. In essence the same system as used on the earlier Boeing 377, the code consisted of two digits affixed to the model number to identify the specific aircraft version. For example, was assigned code "21". Thus, a 707-320B sold to Pan Am had the model number 707-321B. The number remained constant as further aircraft were purchased; thus, when Pan American purchased the 747-100, it had the model number 747-121. In the 1980s, the USAF acquired around 250 used 707s to provide replacement turbofan engines for the program. The 707 is no longer operated by major airlines. American actor owned an ex-Qantas 707-138B, with the registration N707JT. In May 2017, he donated the plane to the near Wollongong, Australia. The plane will be flown to , where HARS is based, once repairs to ensure safe flying condition have been completed. Orders and deliveries[] Deliveries[] 707 Model summary[]